From f0cb32207307e9d7b3ee8117078b7a37f8d0166e Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Tue, 20 Oct 2015 15:23:51 +0200 Subject: genirq: Implement irq_percpu_is_enabled() Certain interrupt controller drivers have a register set that does not make it easy to save/restore the mask of enabled/disabled interrupts at suspend/resume time. At resume time, such drivers rely on the core kernel irq subsystem to tell whether such or such interrupt is enabled or not, in order to restore the proper state in the interrupt controller register. While the irqd_irq_disabled() provides the relevant information for global interrupts, there is no similar function to query the enabled/disabled state of a per-CPU interrupt. Therefore, this commit complements the percpu_irq API with an irq_percpu_is_enabled() function. [ tglx: Simplified the implementation and added kerneldoc ] Signed-off-by: Thomas Petazzoni Cc: linux-arm-kernel@lists.infradead.org Cc: Tawfik Bayouk Cc: Nadav Haklai Cc: Lior Amsalem Cc: Andrew Lunn Cc: Sebastian Hesselbarth Cc: Gregory Clement Cc: Jason Cooper Cc: Marc Zyngier Link: http://lkml.kernel.org/r/1445347435-2333-2-git-send-email-thomas.petazzoni@free-electrons.com Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'kernel/irq/manage.c') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0eebaeef317b..c84670c373f9 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1743,6 +1743,31 @@ out: } EXPORT_SYMBOL_GPL(enable_percpu_irq); +/** + * irq_percpu_is_enabled - Check whether the per cpu irq is enabled + * @irq: Linux irq number to check for + * + * Must be called from a non migratable context. Returns the enable + * state of a per cpu interrupt on the current cpu. + */ +bool irq_percpu_is_enabled(unsigned int irq) +{ + unsigned int cpu = smp_processor_id(); + struct irq_desc *desc; + unsigned long flags; + bool is_enabled; + + desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU); + if (!desc) + return false; + + is_enabled = cpumask_test_cpu(cpu, desc->percpu_enabled); + irq_put_desc_unlock(desc, flags); + + return is_enabled; +} +EXPORT_SYMBOL_GPL(irq_percpu_is_enabled); + void disable_percpu_irq(unsigned int irq) { unsigned int cpu = smp_processor_id(); -- cgit v1.2.3 From abc7e40c81d113ef4bacb556f0a77ca63ac81d85 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 13 Dec 2015 18:12:30 +0100 Subject: genirq: Prevent chip buslock deadlock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a interrupt chip utilizes chip->buslock then free_irq() can deadlock in the following way: CPU0 CPU1 interrupt(X) (Shared or spurious) free_irq(X) interrupt_thread(X) chip_bus_lock(X) irq_finalize_oneshot(X) chip_bus_lock(X) synchronize_irq(X) synchronize_irq() waits for the interrupt thread to complete, i.e. forever. Solution is simple: Drop chip_bus_lock() before calling synchronize_irq() as we do with the irq_desc lock. There is nothing to be protected after the point where irq_desc lock has been released. This adds chip_bus_lock/unlock() to the remove_irq() code path, but that's actually correct in the case where remove_irq() is called on such an interrupt. The current users of remove_irq() are not affected as none of those interrupts is on a chip which requires buslock. Reported-by: Fredrik Markström Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org --- kernel/irq/manage.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/irq/manage.c') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0eebaeef317b..6ead200370da 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1434,6 +1434,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) if (!desc) return NULL; + chip_bus_lock(desc); raw_spin_lock_irqsave(&desc->lock, flags); /* @@ -1447,7 +1448,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) if (!action) { WARN(1, "Trying to free already-free IRQ %d\n", irq); raw_spin_unlock_irqrestore(&desc->lock, flags); - + chip_bus_sync_unlock(desc); return NULL; } @@ -1475,6 +1476,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) #endif raw_spin_unlock_irqrestore(&desc->lock, flags); + chip_bus_sync_unlock(desc); unregister_handler_proc(irq, action); @@ -1553,9 +1555,7 @@ void free_irq(unsigned int irq, void *dev_id) desc->affinity_notify = NULL; #endif - chip_bus_lock(desc); kfree(__free_irq(irq, dev_id)); - chip_bus_sync_unlock(desc); } EXPORT_SYMBOL(free_irq); -- cgit v1.2.3